The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
In order to realize more advantages from multi-speed transmissions such as better fuel economy, vehicle responsiveness, and shifting smoothness, a proper gear shift strategy being implemented in a transmission control module is of substantial importance.
The transmission mediates between the engine power and the power demand at the wheels by choosing a suitable gear ratio. Under dynamic driving conditions, the transmission is required to shift in order to match the power requirements commanded by the operator. A gear shift decision is also required to be consistent such that the vehicle can remain in the next gear for a period of time such that a minimum engine speed is maintained during deceleration. This minimum engine speed is based on drivability, NVH and engine stall protection requirements needed to compensate for various vehicle functions which affect engine idle speed.
As transmissions get more gear ratios, e.g., 8, 9, 10, or higher multi-speed transmissions, the task of choosing the most appropriate gear to maintain optimal vehicle responsiveness has become increasingly difficult. Thus, while current strategies for automatically controlling the shift sequencing of transmissions achieve their intended purpose, there is a desire to maintain a target minimum turbine speed during engine deceleration to improve vehicle responsiveness.